During the Great Depression one could see the shuttered factories, and machines sitting idle. At one time most of the shuttered factories were alive and well. The factories had money behind them, the buildings were there all intact, the machines and workers were there, and then bingo they closed the doors, machines quiet, what had changed? The business couldn't sell their product not because people didn't want their product but because they didn't have the money to buy it. Bingo the businss closed up.
What businessmen would continue making products that no one had the money to buy?
Wrong. Much of American industry was heavily leveraged and when the stock market crash wiped out much of America's investment capital, lenders began to call in other debts to cover their losses. When business owners couldn't cover their loans, they were forced to close their doors and liquidate what assets they could, of course, laying off their workers in the process.
Growing the economy from the middle out is political bullshit. You can have all the demand in the world for your product, but if you can't find investors to give you the money to open a factory and cover your operating expenses, nothing will happen. You can have the best idea for a business in the world, but if you can't find investors who will give you start up capital, nothing will happen.
The difference between Obama and Romney, or more broadly between left and right, is that Obama believes the government should tax away some investment capital and direct to politically and ideologically sound investments, such as windmills or solar panels or electric cars and Romney and others on the right believe that private investors risking their own money are more likely to make investments that will produce economic growth than are politicians and bureaucrats, and most of the world agrees with Romney, which is why so many previously central planned economies such as China and Russia are now allowing private investors to determine where investment capital should go.